The present invention relates, in general, to electric power service apparatus for controlling the supply of electrical power to homes and buildings and, more specifically, to watthour meters and watthour meter socket adapters mountable in watthour meter sockets at homes and buildings.
Electrical power is supplied to an individual site by external electrical power line conductors located above or below ground. In a conventional arrangement, electrical power line conductors are connected to contacts in a watthour meter socket mounted on a building wall. Electrical load conductors are connected to another set of contacts in the meter socket and extend to an electrical distribution network in the building. A watthour meter is connected into the contacts in the meter socket to measure the electric power drawn through the load conductors.
Due to the current trend toward the use of plug-in watthour meters, extender type socket adapters have been devised which allow the addition of equipment and features not originally intended for the electrical service. Such watthour meter socket adapters have been constructed as service limiting adapters and provided with power disconnect devices, such as circuit breakers or ground fault circuit interrupters, both for protecting the electrical service as well as, in certain applications, to limit the amount of power supplied to the use site.
It is common in the electrical utility industry to frequently disconnect electrical service to a particular site. Such service disconnection can be for nonpayment, seasonal usage, or rental units in high turnaround areas, such as college campuses, mobile home parks and apartments, etc. Typically, when it is desired to disconnect electrical service to a particular user site, a utility serviceperson goes to the particular site and removes the watthour meter. Another serviceperson must be sent out to re-install a watthour meter to reconnect service to the site. This sequence is labor intensive and, therefore, expensive.
Certain watthour meter sockets are provided with a hand-operated, clamp jaw bypass mechanism which enable a utility to easily bypass the meter by connecting the line conductors directly to the load conductors while the meter is removed for servicing or replacement. The lever clamp bypass mechanism includes a pivotal lever mounted within the socket housing. The lever moves jumpers or bypass conductors between a first position, when the lever is in a downward extending position, in which the bypass conductors are spaced from one pair of the line and load contacts and a second position, when the lever is in an upward extending direction providing a jumper or bypass path between one pair of line and load jaw contacts in the socket. The lever and jaw mechanism may also be provided with or be operative with a jaw clamp device, such as a spring loaded portion of the jaw contacts which securely bias the blade terminals of a watthour meter or meter socket adapter in the socket jaw contacts when the lever is in the first or down position and holds the jaw parts spaced apart when the lever is in the up position for removal or insertion of the meter from or into the jaw contacts.
The bypass jumpers are designed only to bypass the meter while testing or replacement of the meter takes place. The bypass jumpers are not designed to disconnect a load or to reconnect a load in the socket. Indeed, watthour meter sockets typically include a printed label which provides a warning not to use the bypass contacts to disconnect a load.
To properly disconnect a meter service, the main disconnect device must switch the load off. This switch, however, is not always accessible to the utility service person as it is usually mounted in a fuse or circuit breaker box inside of the building. Since the utility may be disconnecting the meter service when the power bill has not been paid, the customer will not usually cooperate with the utility service person and turn the power off himself. If the bypass jumpers are used to disconnect or reconnect the load, an arc can be generated between the jaw contacts and the bypass jumpers causing injury to the utility service person.
For safety purposes, primarily to prevent the watthour meter from being reinstalled into the socket jaw contacts when a load is connected to the load conductors in the building or home which receives power from the socket, a multistep installation procedure has been developed and essentially has become a utility industry standard.
If the watthour meter is installed in the socket when the load conductors connected to the socket are connected to an active load in the home or building, arcing will occur between the meter blade terminals and the socket jaw contacts. Arcing creates an explosive event and gases, which are propelled out of the socket toward the utility serviceman, pose a significant injury potential to the utility serviceperson, as well as a fire hazard.
A prior art meter replacement and reinstallation procedure in a socket having a lever controlled set of jaw bypass contacts uses a conventional socket adapter base having internally mounted jaw contacts connected to blade terminals which project outwardly from the bottom wall of the base for engagement with the socket jaw contacts. The base jaw contacts receive mating blade terminals mounted on a similar base attached to the rear surface of a generally rectangular housing shown in FIG. 1. A one phase, two phase or three phase disconnect switch, having an externally movable lever, is mounted in the housing and has contacts connected between the housing base blade terminals. A handle is mounted on the top of the housing to facilitate installation and removal of the housing with the socket adapter base.
When a watthour meter is to be removed from the socket, the socket mounted bypass lever is moved to the up position. This disengages the blade clamping force from the socket jaw contacts, enabling the meter blade terminals to be easily removed from the socket jaw contacts, and at the same time, closes or electrically connects the bypass jumpers and the jaw contacts.
After the watthour meter has been removed from the socket, the disconnect housing is mounted in the socket adapter base, with the disconnect switch in the “ON” or current carrying position, to provide a closed circuit between the line and load jaw blades in the socket adapter base. The socket adapter base is then mounted in engagement with the socket jaw contacts. The bypass lever is then moved to the down position to open the bypass contacts and to clamp the base blades in the socket jaw contacts. Next, the disconnect switch is moved to the “off” position and the disconnect housing removed from the socket adapter base. The socket cover and a bladed adapter cover are then mounted to the socket. Lastly, a sealing ring in the case of a ring style socket is then mounted on the socket to seal off the socket and to complete the removal of a watthour meter from the socket.
When it is desired to reconnect a watthour meter in the socket, a reverse sequence is employed. The sealing ring, the socket cover and the adapter cover are first removed from the socket. With the disconnect switch in the “OFF” position, the disconnect housing is urged into engagement into the socket adapter base in the socket. The disconnect switch in the disconnect housing is the moved to the “ON” position.
The socket bypass lever is then moved to the up position bringing the bypass contacts into engagement with the socket jaw contacts. Since the disconnect switch had previously been moved to the “ON” position, any potential arcing caused by the slow, manual movement of the bypass contacts into engagement with the socket jaw contacts under an active load is prevented by tripping of the disconnect switch.
With the bypass jumpers engaged with the jaw contacts, both the disconnect housing and the adapter base can be removed from the socket. The watthour meter may then be easily installed into the non-clamped, socket jaw contacts. Next, the bypass lever is moved to the down position removing the bypass contacts from engagement with the socket jaw contacts and allowing the clamp jaw portions to move into secure, biased engagement with the meter blade terminals to securely hold the watthour meter in the socket. Finally, a socket cover and seal are used, as required.
Prior watthour meter bypass disconnects have been provided with printed instructions, usually on a separate card which specify the sequence of operation to remove a meter and to install the bypass disconnect in the socket. However, these devices did not provide both meter disconnect and meter reconnect sequences in a readily visible location for use by any utility service person without requiring a separate instruction card.
Prior meter disconnects have also been provided with lights, typically one for each load phase, which indicate if power is supplied to a load even though the disconnect switch is in the “off” position. Reconnecting a watthour meter into an active load creates the potential for dangerous arcing of the bypass contacts which are not designed to handle instantaneous high currents. However, when using such prior meter disconnect devices, it is up to the utility service person to remember to check the state of the lights at the prior sequence step during the meter disconnect and reconnect operations.
While this procedure and equipment, if properly used, minimizes the possibility of arcing and the explosive generation of gases which could damage the socket as well as possibly injure the service utility person, it is not without certain disadvantages. One problem is that the socket adapter base is not always clamped securely in the socket jaws when the socket bypass lever is moved to the down position during meter disconnect. If this occurs, the socket adapter base has a tendency to pull out of the socket with removal of the disconnect housing from the socket. It is then oftentimes difficult to separate the disconnect housing from the socket adapter base.
Another problem involves the handle on the disconnect housing, which has heretofore been mounted on the top of the housing. Installation and removal forces exerted on the disconnect housing through the handle have a tendency to be applied more through the top portion of the housing and not equally or directed across the front entire housing. This can lead to less than complete engagement of the disconnect housing blades in the socket adapter base jaw contacts.
Since the handle on the prior art disconnect housing has been mounted on top of the housing, the disconnect switch lever sticks out of the front of the housing. This places the disconnect switch lever in a position susceptible to damage during storage and transport of the disconnect housing to and from utility sites.
Thus, it would be desirable to provide a disconnect watthour meter socket adapter which facilitates easy removal and reinstallation of a watthour meter into and out of a watthour meter socket while minimizing the potential for injury to the utility serviceperson and damage to the watthour meter socket or disconnect if the bypass contacts are reconnected under load. It would also be desirable to provide a disconnect watthour meter socket adapter which is capable of diverting arcing gases generated during a meter disconnect or reinstallation away from the utility serviceperson to minimize the potential for injury to the utility serviceperson. It would also be desirable to provide a disconnect watthour meter socket adapter which has a more centralized mounting position of the handle for ease of removal of the disconnect housing from the socket adapter and even mounting force on the disconnect housing in the socket during a meter reconnect procedure. It would also be desirable to provide a disconnect watthour meter socket adapter which protects the disconnect switch lever from contact with external objects so as to minimize the potential for damage to the disconnect switch lever.